Enable UDBServer broadcast

[bastianhjaeger]

In case one needs to broadcast and receive messages, this solution is what I came up with so far.

#include <thread>
#include <chrono>
#include <string>

#include <mav/UDPServer.h>

using namespace std::chrono;

mav::MessageSet message_set_{"mavlink/common.xml"};

void receive_thread_function(mav::MessageSet& message_set,  mav::NetworkInterface& network_interface) {
    mav::StreamParser parser(message_set, network_interface);
    while (1) {
        mav::Message message = parser.next();
        std::cout << "received " << message.name() << " (" << message.id() << ") from" << std::endl
                  << " IP " << message.source().toString() << std::endl
                  << " systemId " << (int)message.header().systemId() << std::endl
                  << " componentId " << (int)message.header().componentId() << std::endl << std::endl;
    }
}

int main() {
    const char* broadcast_ip = std::getenv("BROADCAST_IP");
    const uint16_t broadcast_port = static_cast<uint16_t>(std::stoi(std::getenv("BROADCAST_PORT")));

    const uint16_t sys_id = static_cast<uint16_t>(std::getenv("SYS_ID") ? std::stoi(std::getenv("SYS_ID")) : 1);
    const uint16_t comp_id = static_cast<uint16_t>(message_set_.e("MAV_COMP_ID_USER1"));

    const mav::Identifier identifier{sys_id, comp_id};

    struct in_addr addr{};
    if (inet_pton(AF_INET, broadcast_ip, &addr) != 1) {
        perror("inet_pton failed");
        return 1;
    }
    mav::ConnectionPartner broadcast_target(addr.s_addr, htons(broadcast_port), false);

    mav::UDPServer network_interface = mav::UDPServer(broadcast_port, broadcast_ip);
  
    std::thread receive_thread = std::thread{[&network_interface]() {
        receive_thread_function(message_set_, network_interface);
    }};

    while(1) {
        std::cout << "Send HEARTBEAT" << std::endl;
        auto message = message_set_.create("HEARTBEAT") ({});

        const int wire_length = static_cast<int>(message.finalize(0, identifier));
        network_interface.send(message.data(), wire_length, broadcast_target);

        std::this_thread::sleep_for(1000ms);
    }

    return 0;
}

[tobias-auterion]

Nice, thanks. Looks good to me.